I have seen a great number of air-intakes for ventilation systems here in the US that all look alike: A duct protruding a wall; sometimes with a grille to keep debris out, sometimes cut at an angle or decorated to stand out as an architectural gesture. (FYI, the lip shown above in the image is the underside of an exterior metal window sill.)
During my visit to Germany I came across this intake, that also doubles as a filter for pollen and particles. I thought this was a neat idea and worth replicating, even if the design of the box could use a little bit of design attention. The filters in HRV or ERV machines are not really meant to take care of these pollutants and by the time they get to the equipment, they are already inside the duct-system. I have yet to locate a resource for such a product in the US—the model shown is made by a company named Paul in Germany.